I trust you are being sarcastic? How did the last 15-20 BOE not have a "cataclysmic impact on the Earth's biota, fauna" and the last 3 on "us", but this one will?

<snip>

Is this some sort of end-of-world cultism that has taken hold in this thread?

Not sarcastic....

Well I tend to be more tongue in cheek than not.

And I think we are mostly in agreement as you yourself point out.

With all the noise I'm not surprised that you've missed what I posted earlier, with links to various papers, including one that seems to dismiss BOE in both the Eemian and the Holocene.

But there are more papers that can be found online that point in another direction, and the remains of wave action along the north coast of Greenland from the Holocene Maximum is strongly indicative of a BOE.

And the opposite point: If there were no BOEs in this or recent interglacials when the Arctic was significantly warmer than it is today, then a BOE is by the same token not very likely in the next few decades.

Saw that and started digesting them last night. While I hope you are right about a BoE, in the same breath, both of our analysis suggest one is not necessary for catastrophic climate change to occur. (And in fact, is currently underway...)

Here's a link to a review article (an article that examines recent studies and summarizes them) published in the journal "Climate Change Reports" in December 2018. The article examines whether an ice-free Arctic leads to "tipping point" behavior and concludes that it doesn't.

Actually, it doesn’t. The limitations of the study are bounded by the conditions it studied. These include limitations to a data set of only variably ice covered Arctic, linearity in response in that regime, and omission of other factors not studied that might cause non-linearities and tipping points. They did go beyond those bounds in projecting an ice free arctic from July to December at +4C. But that projection too must be taken in the context of the studies limitations. In other words, that is a lower bound. Feedbacks and inputs leading to nonlinear behavior were excluded.

Said differently, the study creates a linear model based on the observational period. Arguments beyond the observational period conditions are at best speculative. To use the model to argue that tipping point behavior won’t occur falls victim of a self referential error in logic of the type: “We made a model. The model only includes linear response. The model doesn’t predict nonlinear response. Therefore nonlinear response is not possible.” Gack!

Sadly, this sort of error is common, as is the error of extrapolating beyond the bounds of the data set and trying to apply the data set to regimes where it may not and likely does not apply.

If there is little prospect for coal use to decline much in the short-to-medium-term, a new phase of growth also looks unlikely. Coal financing is drying up quickly. And India, one of coal's last growth centres, continues to cancel coal plant openings.

"The fight is coming to an end game," says Tim Buckley, director of energy finance studies at environmental economics think tank Ieefa in Sydney. "India began this decade with over 600GW of planned capacity, and 85pc of those proposals have either been shelved or cancelled. The banking sector collectively in India has $100bn of impaired exposure to the coal sector. So, they have got no new capacity to lend for coal fired projects."

Buckley's preferred measure to track the coal plant pipeline is to compare closures to final investment decisions, or FIDs, on any new plant completions. Because FIDs are declining, and because closures are rising, he calculates that, around 2021, closures will fully outpace openings. "Closures accelerated the last 4 years by 50pc compared to the previous 4 years," says Buckley, adding that "there are now 113 institutions that will no longer provide financing to coal".

In Buckley's view, coal's fortunes are most closely tied to capital availability. The financing sector can see significant risk, he says, that any new coal plant, proposed to open four years from now, begins its life-cycle in a fundamentally uneconomic position, unable to compete with ultra-cheap wind and solar, or in regions with carbon pricing, natural gas. In short, why bother?

Here's some good news that gets overlooked amid current emissions. Current energy investments in fossil fuels and renewables will significantly lower future carbon emissions and are projected to meet the 2C target.

The Washington PostThe World’s Last Coal Plant Will Soon Be BuiltBy David Fickling | BloombergMay 15Fossil-fuel advocates have a favorite rejoinder to those who predict a global shift to renewable energy: Coal has never been more popular.

It’s a decent argument because it happens to be true. While coal-fired power has declined by nearly a quarter in Europe and almost 40 percent in North America over the past decade, the change has been overwhelmed by a 63 percent increase in Asia.

Quote

The tide may finally be turning, though. Final investment decisions, or FIDs, for coal plants have fallen by about three-quarters over the past three years, from about 88GW over the course of 2015 to around 22GW in 2018, according to the International Energy Agency’s latest world investment report released this week.

The full significance of that figure isn’t apparent until you compare it to the pace at which plants are shutting down. Some 30GW of generators were retired last year, so more capacity was closed in 2018 than was approved – almost certainly the first time this has happened in a generation, and possibly the first time since the 19th century. When FIDs drop to zero, the 140-year era of coal plant construction will finally be over.(2)

It will take a few years for that to work its way through the system, since plants typically take about four years to build after reaching FID. Still, the peak in global plant capacity could be just months away.

Quote

Still, that’s not the way that financial decisions are pointing. The top line of the IEA report is that energy investment in general is falling short – renewables spending, for instance, needs to double by 2025 to get the world on track below 2 degrees of warming. But the deeper story is of an energy industry whose bean counters seem to be betting on a sharp decline in fossil fuel use, even as policymakers track a less ambitious path.

Annual FIDs for coal-fired power are already below where the IEA expects them to be seven years from now under its New Policies Scenario, which envisages countries making somewhat more ambitious emissions cuts than are currently in place. That suggests spending is likely to wind up closer to its Sustainable Development Scenario or SDS, an alternative model that would target global temperature increases below 2 degrees.(1)

Indeed, to judge by the slow pace of recent investments in gas-fired power and new oil and gas production, it looks like energy companies are treating the SDS as their central case. That would be an extraordinary outcome, suggesting that a mere continuation of current trends in fossil-fuel investment would be enough to hit the IEA’s most ambitious major climate target.

Here's a link to a review article (an article that examines recent studies and summarizes them) published in the journal "Climate Change Reports" in December 2018. The article examines whether an ice-free Arctic leads to "tipping point" behavior and concludes that it doesn't.

Actually, it doesn’t. The limitations of the study are bounded by the conditions it studied. These include limitations to a data set of only variably ice covered Arctic, linearity in response in that regime, and omission of other factors not studied that might cause non-linearities and tipping points. They did go beyond those bounds in projecting an ice free arctic from July to December at +4C. But that projection too must be taken in the context of the studies limitations. In other words, that is a lower bound. Feedbacks and inputs leading to nonlinear behavior were excluded.

Said differently, the study creates a linear model based on the observational period. Arguments beyond the observational period conditions are at best speculative. To use the model to argue that tipping point behavior won’t occur falls victim of a self referential error in logic of the type: “We made a model. The model only includes linear response. The model doesn’t predict nonlinear response. Therefore nonlinear response is not possible.” Gack!

Sadly, this sort of error is common, as is the error of extrapolating beyond the bounds of the data set and trying to apply the data set to regimes where it may not and likely does not apply.

Sam

Sam,

They used a wide range of models. Are you saying that you don't believe climate models? If so, what scientific based method do you use to make your projections?

Also, the models used were Global Climate Models, and included global responses to projected future forcings. These models often show non-linear behavior in climate responses to forcings. In this case, they show a clear linear relationship between global temperature increase and Arctic ice cover.

From the article:

Quote

Past Evolution of the Sea-Ice Cover

The major role of changes in the external forcing for the past evolution of Arctic sea ice has been identified both in the observational record and in model simulations. In particular, both in models and in observations the Arctic sea-ice coverage (i.e., sea-ice area or sea-ice extent) during summer is linearly related to the rise in global-mean temperature [3, 11, 12, 22, 30, 31, 32]. [14] suggest a simple conceptual model to explain the linearity, establishing an underlying causal relationship between temperature rise and Arctic sea-ice loss. Linear correlations have also been established between the evolution of Arctic summer sea ice and atmospheric CO2 concentration [26, 33] and cumulative anthropogenic CO2 emissions [14, 34, 35]. These individual correlations are directly related to each other, because anthropogenic emissions of CO2 are also the main driver of the observed warming of the atmosphere [27], and the relationship between temperature rise and CO2 emissions has been largely linear in the past.

The linear relationships between the external drivers and Arctic sea-ice coverage do not only hold during summer, but have been shown to hold for all months, both for temperature [36] and for cumulative CO2 emissions [37]. For the linear regression against CO2, R2 values range between 0.75 and 0.92 for every month of the year over the period 1953–2017 [37]. This suggests that the majority of the ice loss across all seasons can directly be explained by the anthropogenic release of CO2.

Do you have any peer-reviewed studies published after December 2018 to indicate this science is wrong?

I do use models. I am decidedly not a great fan of models of any kind. They always need to be sanity checked against reality. Models nearly always have embedded in them serious limitations that are often not fully recognized or described. Very often perceptual and belief systems biases result in unstated presumptions and assumptions that strongly affect or limit them.

And in this I am not specifically or even majorly focusing on climate models. Their limitations are greater than most. More I am referring to a huge array of models that I have personally worked with over the last 40 years. In my youth I trusted them far more than I should have. In a couple of cases that misplaced trust nearly got me killed. I developed a strong skepticism as a result. I still used models. They are incredibly valuable. However, I do not place faith in them.

Extrapolating models beyond their proven basis conditions is particularly dangerous. For climate that now is required if we are to have any guidance from them at all. That does not mean using them blindly without thoroughly and critically analyzing them and their origins. By that I mean especially looking for unstated unconscious biases and errors.

Any statements like “we must assume that...” are huge red flags. And I am not saying this happened here.

But so too are things like creating a linear model from chaotic data and then concluding based on that model that nonlinearities will not arise under radically changed conditions.

I do use models. I am decidedly not a great fan of models of any kind. They always need to be sanity checked against reality. Models nearly always have embedded in them serious limitations that are often not fully recognized or described. Very often perceptual and belief systems biases result in unstated presumptions and assumptions that strongly affect or limit them.

And in this I am not specifically or even majorly focusing on climate models. Their limitations are greater than most. More I am referring to a huge array of models that I have personally worked with over the last 40 years. In my youth I trusted them far more than I should have. In a couple of cases that misplaced trust nearly got me killed. I developed a strong skepticism as a result. I still used models. They are incredibly valuable. However, I do not place faith in them.

Extrapolating models beyond their proven basis conditions is particularly dangerous. For climate that now is required if we are to have any guidance from them at all. That does not mean using them blindly without thoroughly and critically analyzing them and their origins. By that I mean especially looking for unstated unconscious biases and errors.

Any statements like “we must assume that...” are huge red flags. And I am not saying this happened here.

But so too are things like creating a linear model from chaotic data and then concluding based on that model that nonlinearities will not arise under radically changed conditions.

Sam

Sam,

Hard to argue with that. Really hard. Unless you have access to a time machine, models are all we have to project the future.

There are either two things seriously wrong with this model or I have a serious misunderstanding of how the arctic works.1.

The melting season over the Arctic starts somewhere in April. By May the periphery is melting fast and the inside forming meltponds. By June, CAB melting begins. This melting has one principal culprit, the sun. Of course most of that sun energy is returned back to space due to the high albedo of ice, but even then, there is enough heat to melt the ice.

This paper removes the ice on July 1st, because if they remove the ice before then refreezing begins. How? How in the world they remove all the ice during solstice and refreeze begins but if they do it 10 days later refreeze doesn't?

From the paper:

Quote

To examine the recovery mechanisms of Arctic summer sea ice, we simulate the consequences of an ice‐free Arctic Ocean during summer. We set up experiments to start on 1st July from initial conditions that are taken from the reference run, but are perturbed by converting the entire Northern Hemisphere sea ice to water with the same properties as the sea surface water below the ice. Such conversion of relatively fresh sea ice to salty sea water has the advantage of leaving the properties of sea surface water unchanged. The start date is chosen such that the effect of the perturbation is maximal: starting from ice‐free conditions earlier in the year leads to immediate re‐freezing,

This makes no physical sense. By june 21st, with the arctic full of meters thick, cold ice with high albedo, there is more than enough melting to spread across the whole arctic. However this model says that if all ice was removed by the 21st of june refreeze would immediately begin?

What am I missing?

2.

From the article and very important because all the paper I've seen are counting on negative auto correlation:

Quote

For SAT a large positive anomaly occurs between October and February after the initial perturbation, with a peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability.

This does not match the reality observed during winter since 2016. We have seen how the Chukchi remains very warm, way past November, even with a giant mass of ice to the North.

We are also starting to see the accumulation of heat are having long term effect in the Bering and Chukchi.

Logged

I am an energy reservoir seemingly intent on lowering entropy for self preservation.

I'll just want to ask again, how did Hippos got to England during the peak of the eemian? Did they take a flight there or did it take many generations of warming to slowly migrate the hippos to England?

Past warming episode are poor analogues for what we are seeing today. In fact it can be argued that these climatic changes are what made humans a global species. Over thousands of years generations of humans had to move as the climate around them changed.

Today, the change is happening at 100 (1000 after a BOE) times the speed of past change and we are not nomads. We have settled cities counting on the climate to remain within its boundaries for as long as possible. Climate change changes that. But even if we were nomads, the planet is full. All the good places are taken.

Logged

I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Hard to argue with that. Really hard. Unless you have access to a time machine, models are all we have to project the future.

Ken

And so it is that we use them, being ever mindful of their limitations. Even then, we will miss stuff, sometimes really important stuff. And we learn.

It is hugely tempting sometimes to substitute the model for reality. That is always dangerous. Sometimes we forget just how dangerous.

Reality is. Reality is always the gold standard. Reality is. Reality is messy and hard. Sometimes we can reach an understanding of reality from the level of first principles. Even then, substituting models of those laws runs the serious risk of getting things entirely wrong.

Models emulate reality to varying degrees of fidelity under varying limitations and conditions. They are immensely useful. But they do not control reality. Reality imposes limits on them, to the degree they are able to represent reality. Often, the simplifications that the models include are useful in highlighting really really important simple principles, e.g. the first order linear response the authors noted, within the bounds of the data sets they used. And those give us great insights.

But, and it is a big caveat, they do not govern, and they do not easily extrapolate beyond the limitations of conditions under which the original data was gathered. We can and often must extrapolate. In doing so, it is vital that we know that we are doing so, and that we constantly sanity check the results. Simple assumptions, or more often unrecognized and unstated assumptions, may and often do rear their very ugly heads if we extrapolate too far from the data set.

Changes in state and condition generally render the models invalid. Following the state or condition change, a new model is needed. That may be identical to the previous model. Usually it isn’t. Often it is radically different in form. Examples of this occur all over the place. Some of these include:

A) The physics and condition changes in the atmosphere on either side of a supersonic shock boundary. This is encountered with all supersonic craft. The equations are unusual but straight forward.

B) Water flow through soil under advective conditions encountering a paleosol boundary, and entering a different strata underneath it. In this case, at least three models are needed (more likely four of five, or more): one for the adjective transport, one for encounter with the boundary, one for the transport on the boundary, one for entry into the boundary layer, one for transport through the paleosol boundary, one for encounter with the bottom boundary, one for movement in the paleosol laterally, one for movement through the paleosol boundary with underlying sediment, one for entry into the underlying sediment, and or transport on the boundary, and one for transport through the underlying soil. That’s twelve in total that may be important (there may be several more that are essential, and that is based on a homogenous unfractured soil).

There are scale changes between these that render gridded analysis invalid. It may be possible to emulate this with simpler models under certain conditions. But, using simpler models hand waves over key factors which may then make the simplified model completely inaccurate with a change of conditions. (E.g. flooded flow, versus dry conditions, versus variable conditions, ...). And that all excludes other factors such as barometric oscillation, temperature oscillation affecting vapor production and transport, or condensation ... let alone factors such as vegetation, microbial growth, chemical deposition and redissolution ...

C) Cloud formation modeling ... now there is a tough one.

On first blush it might appear that these are ordered from hardest to simplest. In reality, it is the other way around. The fine scale variations in B) and C) make them much more challenging.

Worse, these days we lean heavily on computational models. That wasn’t always the case. Computational models most often are created from gridded multidimensional arrays. The number of nodes, their spacing, and the property calculations at each node accumulate quickly. The total size of the computational space then becomes huge. And so, the number of nodes are reduced and the properties are averaged across the volume.

If done correctly, this is useful. If done incorrectly, all manner of insanity can be hidden. Often, as in the case of soils, fine scale changes must be modeled at their scale. This imposes limitations on the reduction in the number of nodes in the model that render the model unworkable. But keeping the nodes at the required spacing is also unworkable. There are more of them than all of the computers in the world could calculate in a lifetime. So, compromises are made. But, those compromises can do silly things like averaging logarithmic or nonlinear parameters. Nope. That doesn’t work. But it happens all of the time. Etc...

Worse, the time step used must be correlated with the spatial step in certain ways to prevent impossibilities and insanities from occurring in the math. These are easy to miss.

Bounds checking is often turned off to speed the code execution. This hides all manner of other errors, such as indexing beyond the bounds of the computational matrix, and divide by zero errors. That’s not good. Efforts are made to avoid those blunders. And sometimes they still slip through.

And through it all uncertainties accumulate. Some models propagate these. Most do not. Instead they attempt to rely on a variation of parameters method using Monte Carlo and a latin hypercube approach to estimate the uncertainty. This greatly understates the uncertainty though as it hand waves away much of the very real uncertainty. Some approaches such as USGS’s Jupiter Suite that uses multi-model comparison to better estimate uncertainty are better. These are seldom used.

Instead, the all too common approach is to further simplify the model structure, rely on sensitivity calculation to substitute for uncertainty estimation, and shift to Bayesian methods that further obscure or discard uncertainty. Those models are particularly vulnerable to errors in their design.

There are either two things seriously wrong with this model or I have a serious misunderstanding of how the arctic works.1.

The melting season over the Arctic starts somewhere in April. By May the periphery is melting fast and the inside forming meltponds. By June, CAB melting begins. This melting has one principal culprit, the sun. Of course most of that sun energy is returned back to space due to the high albedo of ice, but even then, there is enough heat to melt the ice.

This paper removes the ice on July 1st, because if they remove the ice before then refreezing begins. How? How in the world they remove all the ice during solstice and refreeze begins but if they do it 10 days later refreeze doesn't?

From the paper:

Quote

To examine the recovery mechanisms of Arctic summer sea ice, we simulate the consequences of an ice‐free Arctic Ocean during summer. We set up experiments to start on 1st July from initial conditions that are taken from the reference run, but are perturbed by converting the entire Northern Hemisphere sea ice to water with the same properties as the sea surface water below the ice. Such conversion of relatively fresh sea ice to salty sea water has the advantage of leaving the properties of sea surface water unchanged. The start date is chosen such that the effect of the perturbation is maximal: starting from ice‐free conditions earlier in the year leads to immediate re‐freezing,

This makes no physical sense. By june 21st, with the arctic full of meters thick, cold ice with high albedo, there is more than enough melting to spread across the whole arctic. However this model says that if all ice was removed by the 21st of june refreeze would immediately begin?

What am I missing?

The hottest time of the day isn't noon, it's approximately 3PM in temperate zones. If noon = June 21 at the North Pole, 3PM would be a bit later.

We all know that the sun is at its highest point in the sky at noon, so that must be the hottest time of the day, right? Not really.

While it is true that the most energy being received by the earth from the sun is at noon, the thermal response means that all that energy isn’t felt in the air for at least a few hours. So, if you add three or four hours to noon, you get 3 or 4 p.m.

There are either two things seriously wrong with this model or I have a serious misunderstanding of how the arctic works.

2.

From the article and very important because all the paper I've seen are counting on negative auto correlation:

Quote

For SAT a large positive anomaly occurs between October and February after the initial perturbation, with a peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability.

This does not match the reality observed during winter since 2016. We have seen how the Chukchi remains very warm, way past November, even with a giant mass of ice to the North.

We are also starting to see the accumulation of heat are having long term effect in the Bering and Chukchi.

While it is true that the most energy being received by the earth from the sun is at noon, the thermal response means that all that energy isn’t felt in the air for at least a few hours. So, if you add three or four hours to noon, you get 3 or 4 p.m.

The thermal response of the Arctic to the sun begins when the melting season begins, April in the outer periphery, May in the inner Arctic. By June melting is everywhere, that means the thermal response is everywhere. We don't see it in temperatures because the ice must melt before temperatures can rise.

The only other source for cold is the snow of the continents. May most of the snow is already gone and the ASI is the only source of cold that must be overcome by thermal inertia.

This study has a source of cold that makes the ice return during solistice. I imagine the same source keeps the ocean of almost 0 albedo at barely 2k warmer, even when we have seen the anomalies that can form.

Logged

I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Our results suggest that anomalous loss of Arctic sea ice during a single summer is reversible, as the ice–albedo feedback is alleviated by large‐scale recovery mechanisms.

Please correct me if I'm wrong, but what I read here is that if the ice disappears but everything else stays about the same, the ice will recover. What if the ice disappears because conditions got so bad that the ice melted? And what if the conditions persist the following year with a Arctic ocean full of thin, mobile, transparent ice?

This conclusion does not follow:

Quote

Hence, hysteretic threshold behavior (or a “tipping point”) is unlikely to occur during the decline of Arctic summer sea‐ice cover in the 21st century.

It is unlikely that the ice disappears anomalously. It is likely that the ice will disappear when the conditions for melting are met.

Quote

In this reference run, annual mean surface air temperature in the Arctic rises from −14°C in the 1900s to −4°C in the 2090s. Arctic sea‐ice extent declines, and the Arctic Ocean is typically ice‐free by the end of summer from 2070 onward

This is terrifying to me. Why was this model so wrong? 2070 sounds like a terrible under estimation after seeing the 2010's.

Quote

The start date is chosen such that the effect of the perturbation is maximal: starting from ice‐free conditions earlier in the year leads to immediate re‐freezing, and hence both earlier and later start dates imply shorter exposure of open water to sunlight, and a less pronounced ice–albedo effect.

This again. If all of the Arctic ocean is ice free, maximum exposure of open water to sunlight is on June 21. June 10th? would have the same exposure to the sun as July 1st. This is a simple astronomical fact. Why are they using it as an explanation?

Quote

[14] All our experiments start from sea‐ice free conditions on 1st July. As expected, the Arctic Ocean remains ice‐free for several months, and significant sea‐ice cover does not develop before November.

I believe the November start day for freezing onset. It will be dark and cold regardless of BOE. I also believe fast freezing in extent. Volume will rise fast, but thickness won't go much more than 2m for the same reason. Thin ice thickens fast, but thick ice thickens slow and the time for thickening was cut short by the November start day. Come the melting season it will be thin, warm, first year ice across the whole arctic.

At this point I'm done with this paper until the start date for the simulation is correctly explained.

Now I'm going to look for the other papers crandles posted.

Maybe my answers are there.

Logged

I am an energy reservoir seemingly intent on lowering entropy for self preservation.

There are either two things seriously wrong with this model or I have a serious misunderstanding of how the arctic works.1.

The melting season over the Arctic starts somewhere in April. By May the periphery is melting fast and the inside forming meltponds. By June, CAB melting begins. This melting has one principal culprit, the sun. Of course most of that sun energy is returned back to space due to the high albedo of ice, but even then, there is enough heat to melt the ice.

This paper removes the ice on July 1st, because if they remove the ice before then refreezing begins. How? How in the world they remove all the ice during solstice and refreeze begins but if they do it 10 days later refreeze doesn't?

From the paper:

Quote

To examine the recovery mechanisms of Arctic summer sea ice, we simulate the consequences of an ice‐free Arctic Ocean during summer. We set up experiments to start on 1st July from initial conditions that are taken from the reference run, but are perturbed by converting the entire Northern Hemisphere sea ice to water with the same properties as the sea surface water below the ice. Such conversion of relatively fresh sea ice to salty sea water has the advantage of leaving the properties of sea surface water unchanged. The start date is chosen such that the effect of the perturbation is maximal: starting from ice‐free conditions earlier in the year leads to immediate re‐freezing,

This makes no physical sense. By june 21st, with the arctic full of meters thick, cold ice with high albedo, there is more than enough melting to spread across the whole arctic. However this model says that if all ice was removed by the 21st of june refreeze would immediately begin?

What am I missing?

2.

From the article and very important because all the paper I've seen are counting on negative auto correlation:

Quote

For SAT a large positive anomaly occurs between October and February after the initial perturbation, with a peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability.

This does not match the reality observed during winter since 2016. We have seen how the Chukchi remains very warm, way past November, even with a giant mass of ice to the North.

We are also starting to see the accumulation of heat are having long term effect in the Bering and Chukchi.

This is Tietsche et al paper not Schroeder & Connolley.

With 1. I agree that seems very surprising. If they were converting sea ice (pretty fresh) and simply dumping that as water in liquid form of the same salinity as the sea ice and at the temperature of the salt water below the ice then yes fresh water at -1.7C would freeze. However they say they are making the water as salty as the water below it so that shouldn't freeze. Would a slight pressure difference make the difference between surface water freezing while just below the sea ice it stays liquid?

This does feel like there is a mistake of some sort here. Perhaps the best way to resolve this is to email steffen.tietsche at zmaw.de and ask.

Schroeder & Connolley paper does things differently;

Quote

Four sensitivity experiments were performed in which all the initial sea ice was removed on December 1st (starting time of Ctrl run), March 1st, June 1st and September 1st, respectively.

They also did

Quote

[8] The preceding experiments were somewhat unrealistic because although the ice was removed, the ocean was still in a state compatible with ice cover. Hence, in the following experiments the ocean temperature will be modified to examine an ice‐free situation in the real world where an ice anomaly is connected with an ocean heat anomaly. Where and how should the ocean temperature be modified to simulate a realistic ice‐free situation? To answer this question the annual cycle of the ocean is analysed in the transitional zone with seasonal sea ice (not shown). The uppermost 200 m of the polar oceans are affected by seasonal changes in the HadCM3 run. A maximum ocean temperature of about 3°C is reached in areas which are seasonally covered by sea ice. Based on these findings two further sensitivity experiments are performed in which the initial global sea ice is removed and the ocean temperature of the uppermost 200 m (10 model levels) is artificially increased to a minimum value of 3°C on March 1st and September 1st, respectively. The initial salinity and ocean circulation remain the same as in the Ctrl run.

Here the anomalies persist a few more years, but the size of the sudden forced departure is clearly much larger.

I am feeling that Tietsche et al could have done more to make the departure larger by starting earlier and adding .1C or .2C to the temperature to stop an immediate refreeze. If that is correct and they could have done more, does it matter to the conclusions of the paper? It is still a huge departure from normal conditions and it still recovers pretty rapidly. And the Scroeder and Connolley have done similar but larger departures with similar results.

Re 2:I am not sure I am understanding your point.>"We have seen how the Chukchi remains very warm, way past November"and"peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability"

Seems pretty sensible to me: the peak of the anomaly is in November as you are pointing out. The higher temperature then radiates more heat to space resulting in the temperature anomaly disappearing over the next month or so. After that there is still a difference in the thickness of the ice. The anomalously thin ice ice results in extra heat loss (there is less insulating ice) which means more ice forms at a faster rate so the ice thickness anomaly largely disappears over the following month or so. If there is less snow supported by the newer ice, that newer ice may grow thicker.

If the sun was the only source of heat, you might expect the peak of the anomaly to be around end of September/ early October when the sun sets. However there is also downwards longwave radiation from the atmosphere, and with large areas largely ice free, it doesn't seem unreasonable for this to go on increasing the size of the peak anomaly a bit longer via the temperature dropping more slowly such that the size of the anomaly increases into November.

Please correct me if I'm wrong, but what I read here is that if the ice disappears but everything else stays about the same, the ice will recover. What if the ice disappears because conditions got so bad that the ice melted? And what if the conditions persist the following year with a Arctic ocean full of thin, mobile, transparent ice?

This conclusion does not follow:

Quote

Hence, hysteretic threshold behavior (or a “tipping point”) is unlikely to occur during the decline of Arctic summer sea‐ice cover in the 21st century.

It is unlikely that the ice disappears anomalously. It is likely that the ice will disappear when the conditions for melting are met.

Yes I agree it is true that "It is unlikely that the ice disappears anomalously. It is likely that the ice will disappear when the conditions for melting are met."

However, the paper is looking at hysteresis and concluding hysteresis behaviour is unlikely so the sentence with the word hysteretic in it, is supported. Disturb it from equilibrium and it pretty well goes back to its equilibrium position.

>What if the ice disappears because conditions got so bad that the ice melted?Is just a completely different question.

In this reference run, annual mean surface air temperature in the Arctic rises from −14°C in the 1900s to −4°C in the 2090s. Arctic sea‐ice extent declines, and the Arctic Ocean is typically ice‐free by the end of summer from 2070 onward

This is terrifying to me. Why was this model so wrong? 2070 sounds like a terrible under estimation after seeing the 2010's.

Those dmi graph temperatures are not properly averaged, they give far too much weight to temperatures very close to the poll. Not sure I have a very good handle on what these annual mean temperatures has been and how much they should be expected to change in order to judge whether it is a terrible understatement. You having that reaction doesn't surprise me. I'll have to think about whether there is anything appropriate I can say to provide some explanation.

Crandles I’m working on reply to your papers, I’ll hit you this afternoon, hopefully.

I just wanted to point out how terribly naive and unscientific Binnthos argument is.

1. Rate of change. The ice fee Arctic events he mentioned happened over millennia, not decades. RATE OF CHANGE

Yes, I never said otherwise. But they were none the less BOEs and these BOEs did not lead to an equitable climate.

The rate of change now is increadible, and horribly dangerous. Much more than any BOE that might or might not happen.

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2. The only evidence he presents for “no cataclysm” is the fact that we are here. By that standard an asteroid like the one that killed the dinosaurs will not be cataclysmic

Well I didn't present any evidence for "no cataclysm", I just pointed out that nobody seems to have heard of any such cataclysms, so they can't have been all that bad.

In other words: The former BOEs did not lead to cataclysms. They did not lead to an equitable climate. They just came and nothing much happened. But the "rapid" warming that lead up to these BOEs was very serious, and yet it was only 1/10th or even 1/20th of the current rate.

So again: RATE OF CHANGE is dangerous, not BOE.

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3. He says that because nomadic, hunter gatherer humans survived past climate change, no climatic cataclysm happened. He says so with confidence. Please think about it for one second.

I didn't say that. How desperate can you be when you knock up strawmen all over the place instead of trying to argue your own case?

And yes, of course it is obvious that because the planetary biosphere did not suffer from earlier BOEs then there were no cataclysms. Or do you understand cataclysms as meaning something totally different than other people?

The increadible RATE OF CHANGE of the current AGW has the potential to be truly cataclysmic. But some people want to ignore this, perhaps because of some fundamentalist Christian thing, and instead focus on a future end-of-world event that basically exists only in their own minds.

You seem to be afraid of something happening in 2070? What about being afraid of what is happening now and will continue to become worse until 2070?

Talk about flat-earthers!

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because a thing is eloquently expressed it should not be taken to be as necessarily trueSt. Augustine, Confessions V, 6

Ocean heat hit both ice fronts in October of 2016. We all see it. The official projections have always been wrong. Kick the can down the road. The real world doesn't care.

We're not equipped for this.

New record or not, the atmosphere is already responding to potential temperature and avoiding the Arctic basin. We lost the cold. As a result, the polar cell lost some of its last stability. Incursions of heat straight to the pole for this long ( since May Day).. I don't care what the temp is at 2M over the ice.

The only other source for cold is the snow of the continents. May most of the snow is already gone and the ASI is the only source of cold that must be overcome by thermal inertia.

This study has a source of cold that makes the ice return during solistice. I imagine the same source keeps the ocean of almost 0 albedo at barely 2k warmer, even when we have seen the anomalies that can form.

You do know that there are no "sources" of cold? There are only sources of heat. The universe is incredibly cold everywhere except for nuclear reactors like the Sun (or cooling piles of nuclear waste like the center of the Earth).

So the Arctic during winter will continue to lose heat, and the less sea ice there is at the beginning of winter, the more heat will be lost. This counts as a very strong negative feedback to global warming, somewhat counterbalancing all the positive feedbacks in the Arctic (although not quite overcoming them!)

In a hypothetical equitable climate, the Arctic will lose a hell of a lot more heat during winter than it does now. This heat would have to be advected from lower altitudes. A very strong negative feedback to any global warming.

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because a thing is eloquently expressed it should not be taken to be as necessarily trueSt. Augustine, Confessions V, 6

>What if the ice disappears because conditions got so bad that the ice melted?Is just a completely different question.

But isn't that the question we need answered?

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Schroeder & Connolley paper does things differently;

ok. From the real Connolley paper this time:

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Starting without sea ice in December (blue line) the “normal” sea ice area recovers in only one month in the Arctic

This makes perfect sense. If all the sea ice in the arctic is magically (technical term) removed while leaving the rest of the arctic as in the same state as any freezing season before 2016/17, the ice would indeed return extremely fast. There would be some evaporation and some clouds to retard heat irradiation, but it won't matter. The top layer of the ocean would freeze extremely fast.

The question then becomes, in this simulated scenario how thick will the ice become by April?

Let's assume no clouds form, there is nothing but clear skies, the ocean remains nice and calm, the rest of the NH doesn't exist and all the ice returns by January 1st. Then we assume the ice has 4 months of 2000's level winter. Very cold, no intrusions from the south.

Making a crude visual calculation:

How thick would the ice be come April, with winter like the 2000's?

I estimate about 1.5 meters thick.

Could such ice take a 2000's level summer? How about a 2010's level summer? what about export?

At the very least you must admit that if the ice was magically removed in December, the likelihood of a BOE would be very high. The thin ice would be very vulnerable to even an average melting season.

Next I was expecting to cover what happens when the ice is removed during summer but, alas, This is pretty much all it says:

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A longer‐lasting impact is achieved by removing the sea ice in summer. This is because no sea ice can build up during summer, and if no sea ice is present the reduced surface albedo causes an increase in ocean temperature (up to 2.5 K for the area mean in the Arctic and 1 K in the Antarctic at a depth of 5 m) which delays freezing in the next autumn.

And looking at their graph I can see why they don't talk much about any of the other scenarios

Here it is:

Notice something interesting? Removing ice during either December or June result in a BOE the following year. And the year following that, but they it gets a bit better and it heals.

This defies logic and science. Even under very limited very favorable models used here, hysteresis happens for a few years and then it magically disappears.

This defies belief. I mean, not even a mention of this. They skipped right over the consecutive BOEs to arrive to the conclusion that in a few years the ice would recover. They could have at least mention it.

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I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Are you telling me my “dark sucker” is actually a light source, that it doesn’t suck in the darkness revealing the light? Nah! Can’t be. I’ve heard people call them flashlights or something like that. I thought they were pulling my leg. ;-)

Of course cold is a sink in common as well as engineering parlance. More than that, “cold” relative to “warm” or “hot” is all about less energy in the form of vibration.

In the extreme the absence of vibration is absolute zero. Yet like the arctic ice it is possible to get slightly colder than even that by changes in the spin state of the atoms, although the temperature won’t decline any farther.

But they were none the less BOEs and these BOEs did not lead to an equitable climate.

we will never reach equitable climate in our lifetimes. Only the transition to one.

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The rate of change now is increadible, and horribly dangerous. Much more than any BOE that might or might not happen.

A BOE increases the rate of change.

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Well I didn't present any evidence for "no cataclysm", I just pointed out that nobody seems to have heard of any such cataclysms, so they can't have been all that bad.

Ask the species that preceded the hippo. I bet they found it very cataclysmic, but not more so than the plants that preceded the hippos food. At least the hippos can pick up their stuff and move. The poor plants were stuck in place.

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I didn't say that. How desperate can you be when you knock up strawmen all over the place instead of trying to argue your own case?

I'm trying to drive down the point that you can't compare the effects of climate change on the humans of the time because:

1. They were nomadic and the world was empty, now we are sedentary and the world is full.2. The everything happened over centuries and millennia, not decades.

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And yes, of course it is obvious that because the planetary biosphere did not suffer from earlier BOEs then there were no cataclysms. Or do you understand cataclysms as meaning something totally different than other people?

From the our point of view looking into the past like gods, there was no cataclysm because it happened slowly, giving time for nature to adapt. From the point of view of every organism that failed to adapt to sudden changes of climate for their time scale, it was cataclysm.

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The increadible RATE OF CHANGE of the current AGW has the potential to be truly cataclysmic. But some people want to ignore this, perhaps because of some fundamentalist Christian thing, and instead focus on a future end-of-world event that basically exists only in their own minds.

See my rebuttals to the papers supporting no hysteresis. Your confidence is misplaced. If you have different author, different papers or maybe even a good theory as to how the ice albedo feedback might be overwhelmed, I would like to hear it.

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I am an energy reservoir seemingly intent on lowering entropy for self preservation.

From the our point of view looking into the past like gods, there was no cataclysm because it happened slowly, giving time for nature to adapt. From the point of view of every organism that failed to adapt to sudden changes of climate for their time scale, it was cataclysm.

So it wasn't a cataclysm, it was simply a change that nature adapted to.

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Your confidence is misplaced.

Confidence in what? That humanity and civilization is facing a massive threat at this very moment? Or that a hypothetical non-event (as you seem to have concluded yourself) after several decades will not be worse than what will happen until then?

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because a thing is eloquently expressed it should not be taken to be as necessarily trueSt. Augustine, Confessions V, 6

Of course there are sources of cold. If I have a glass of warm water and I need a source of cold I just go get some ice and throw it in. There. Cold. That energy always flows from hot to cold, that is,the water warms the ice, losing heat, not the other way around is meaningless in this context.

Granted it is nice to remind engineering students of the nature of the flow, but completely useless in this discussion.

Interesting that you are more concerned about the name I give heat sinks, than the fact that the models used to determine risk and action to be taken have heat sinks that don't exist.

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I am an energy reservoir seemingly intent on lowering entropy for self preservation.

From the our point of view looking into the past like gods, there was no cataclysm because it happened slowly, giving time for nature to adapt. From the point of view of every organism that failed to adapt to sudden changes of climate for their time scale, it was cataclysm.

So it wasn't a cataclysm, it was simply a change that nature adapted to.

Bolded the part that you don't want to read or understand, maybe that will help.

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I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Of course there are sources of cold. If I have a glass of warm water and I need a source of cold I just go get some ice and throw it in. There. Cold. That energy always flows from hot to cold, that is,the water warms the ice, losing heat, not the other way around is meaningless in this context.

Granted it is nice to remind engineering students of the nature of the flow, but completely useless in this discussion.

Interesting that you are more concerned about the name I give heat sinks, than the fact that the models used to determine risk and action to be taken have heat sinks that don't exist.

Well, I wasn't sure. You do ramble on a bit, and it gets confusing.

So what are these heat sinks that the scientists see but you don't?

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because a thing is eloquently expressed it should not be taken to be as necessarily trueSt. Augustine, Confessions V, 6

From the our point of view looking into the past like gods, there was no cataclysm because it happened slowly, giving time for nature to adapt. From the point of view of every organism that failed to adapt to sudden changes of climate for their time scale, it was cataclysm.

So it wasn't a cataclysm, it was simply a change that nature adapted to.

Bolded the part that you don't want to read or understand, maybe that will help.

Oh, it was a series of localized cataclysms? How on earth do you understand the word cataclysm? It isn't something that happens here and there, it is something that happens everywhere! Local tragedies do not a cataclysm make!

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because a thing is eloquently expressed it should not be taken to be as necessarily trueSt. Augustine, Confessions V, 6

They chose July 1st as the date for the first removal of the ice and then they claim:

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The start date is chosen such that the effect of the perturbation is maximal: starting from ice‐free conditions earlier in the year leads to immediate re‐freezing, and hence both earlier and later start dates imply shorter exposure of open water to sunlight, and a less pronounced ice–albedo effect.

The day that maximizes open water to sunlight is June 21st. That implication is obviously not true.

« Last Edit: July 25, 2019, 07:20:52 AM by Archimid »

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I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Folks, this thread is deteriorating fast and hard.Sometimes the best answer is to keep mum, and let things sort themselves out. Not every post needs a riposte.The arctic will go BOE in a decade and a half (this was the subject of this thread, not the consequences BTW) and then we can revisit and see who was right.

Ok Oren, will try to ignore the less useful stuff to avoid clutter at the cost of letting untruths slide.

Are there other papers that address an ice free arctic that use significantly different methodology than the two above? Anything not using sea ice perturbation experiments or perhaps more recent models?

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I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Folks, this thread is deteriorating fast and hard.Sometimes the best answer is to keep mum, and let things sort themselves out. Not every post needs a riposte.The arctic will go BOE in a decade and a half (this was the subject of this thread, not the consequences BTW) and then we can revisit and see who was right.

Quite right. I actually think we'll see BOE sooner than that - whether we measure it by less then 1m km2 or a liftoff of DMI north of 80 temps.

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because a thing is eloquently expressed it should not be taken to be as necessarily trueSt. Augustine, Confessions V, 6

Of course there are sources of cold. If I have a glass of warm water and I need a source of cold I just go get some ice and throw it in. <Snippage>

OK, while creative, not really A Thing.

You don't really have "sources of cold" any more than you have "sources of vaccuum". What "cold" indicates is a difference in enthalpy - net heat content components of a system, and thanks to the laws of thermodynamics heat will attempt to equilibrate across it - thus your ice cubes melting.

There wasn't any "cold source" here, just the heat of varying levels being redistributed.

This does bring me to a point which I feel people have been overlooking. It unfortunately is one for which we probably have the least instrumentation for - net enthalpy of the Arctic ocean and surrounding seas.

*This* will be the key factor in the tipping point.

Insolation year over year is virtually constant. How much heat is retained or lost is a factor of our GHG levels and import from outside the Arctic during the refreeze. There is in fact a calculable maximum possible loss which can be determined via calculation of black body radiation per square meter. That can go up, but only if the temperature of the atmosphere goes up.

Further, once you have ice, and then snow cover, the rate of heat flow out of the ocean goes down again. Temperature drops and decreases the flow out of the atmosphere - or the heat source changes by way of the thermal gradient driving more import of heat into the arctic via broad scale convective atmospheric circulation from lower latitudes. When that happens - as we've been starting to see, possibly as far back as the 1990s - the imported heat replaces the losses which normally would come out of the ocean, and enthalpy increases.

So it has been for several years also that I've started becoming a much closer student of winter refreeze and weather conditions, and to a lesser degree have been trying to better understand the changing dynamics of current and salinity. I have a very long way to go.

These I think more than summer melt are the real players - behind the scenes, pulling the levers of the secondary stuff we focus a lot of our attention on.

So again, when a BoE occurs, a great deal else will need to have happened to make it possible. The net sum of those changes will already be driving, have been driving climate changes which are not reversible without our finding a way to dump petajoules of heat out of the ecosystem.

The state of the ice will be a side effect of that, and while no doubt a BoE will help dump more heat into an already overwhelmed system, it will be stacking it on top of an already monumental pile. Absent of this any BoE is simply an anomaly which the system would swallow and then rapidly return to where it was previously.

In a small way, that is *exactly* what we saw in 2012. We were all convinced in 2013 that the End Was Nigh, and there were lots of scary moments which ended in... a bounce back. The heat content of the system at the time is exactly why that happened. If the area loss was the key to tipping the system over, that should have done it, but it didn't. To be clear, I'm not trying to minimize the cascading effect of 2012, which was huge, but rather to put it into what I think is correct context. In that regard, I think if we want to understand the most key drivers behind 2019, we need to go well past 2012, probably at least another decade, possibly two in order to find the build up which led us to where we are now.

So right now you are witnessing the history of previous winters playing out. There is excitement, driven in part by weather, much as in 2012, but again, now as then I think it is the heat the system started with in May that is the hidden power behind what is playing out now.

(Edit: Looking for papers on Arctic Ocean heat content, I found this, which helps partially illustrate where I was trying to take my point.

Could such ice take a 2000's level summer? How about a 2010's level summer? what about export?

At the very least you must admit that if the ice was magically removed in December, the likelihood of a BOE would be very high. The thin ice would be very vulnerable to even an average melting season.

Yes I will admit that likelihood of a BOE would be very high and indeed that is what the model shows:

volume getting up to 1.3 * 10^13 m^3 instead of the normal model level of 1.5 * 10^13 m^3.Not sure I can judge the dates accurately but next summer is ice free for roughly 3 months so the ice starts to form by November if not late October. This gives more time for ice to form so the volume gets up pretty close to the low edge of the normal model range.

sorry mangled that answer confusing blue(1 Dec removal) and black (1 March removal) lines. Model shows after 1 Dec removal volume practically back to normal by May. By September volume at minimum is near 1k km^3 below normal but not by much

1March removal leaves little time for volume build up. This is where volume reached 1.3 vs normal 1.5 *10^13 m^3 by a late maximum in May. This seems surprisingly high to me.

The later sentence

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The preceding experiments were somewhat unrealistic because although the ice was removed, the ocean was still in a state compatible with ice cover.

may have some relevance here.

Anyway not surprising this date of removal has more effect with ice free conditions reached for about 3 months circa Aug-Oct.

1 Sept removal (red line) has least effect, it is straight back to a normal volume certainly by April and perhaps normal as soon as November.

Unsurprisingly, 1 April removal (green) has most effect: There is no significant ice formation til Dec. The next 2 minimum show the green line as lowest just below the normal range then it settles back into the normal range.

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Next I was expecting to cover what happens when the ice is removed during summer but, alas, This is pretty much all it says:

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A longer‐lasting impact is achieved by removing the sea ice in summer. This is because no sea ice can build up during summer, and if no sea ice is present the reduced surface albedo causes an increase in ocean temperature (up to 2.5 K for the area mean in the Arctic and 1 K in the Antarctic at a depth of 5 m) which delays freezing in the next autumn.

And looking at their graph I can see why they don't talk much about any of the other scenarios

Here it is:

Notice something interesting? Removing ice during either December or June result in a BOE the following year. And the year following that, but they it gets a bit better and it heals.

This defies logic and science. Even under very limited very favorable models used here, hysteresis happens for a few years and then it magically disappears.

This defies belief. I mean, not even a mention of this. They skipped right over the consecutive BOEs to arrive to the conclusion that in a few years the ice would recover. They could have at least mention it.

You have read the caption under that figure which says

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Sensitivity experiments without sea ice and modified ocean temperature: time series of ice area (m2), ice volume (m3), and area mean (60°N to 90°N and 60°S to 90°S) ocean temperature at a depth of 5 m and 204 m. The orange area represents the climate of the Ctrl run ± twice the standard deviation. The green area represents the observed mean ice area for the period 1980 to 2000 [Comiso, 2003].

"modified ocean temperature" means this is where they did the extra large departures from normal:

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the initial global sea ice is removed and the ocean temperature of the uppermost 200 m (10 model levels) is artificially increased to a minimum value of 3°C on March 1st and September 1st, respectively.

200m increased to a minimum of 3C, that is huge volume of water to pretty warm temperatures. That is a massive departure from normal conditions. The top 50m (mixed layer) may well cool to close to normal in the first winter but the rest is going to persist at warmer than normal for several years and provide extra heat to the system for several year.

Despite this massive departure from normal, the appropriate conclusion seems to me to be it recovers in just a few years (~8).